package messServer;

//Set up a MessServer that will receive a connection from a client, send 
//a string to the client, and close the connection.
import java.io.EOFException;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class MessServer extends JFrame 
{
private JTextField enterField; // inputs message from user
private JTextArea displayArea; // display information to user
private ObjectOutputStream output; // output stream to client
private ObjectInputStream input; // input stream from client
private ServerSocket server; // server socket
private Socket connection; // connection to client
private int counter = 1; // counter of number of connections

// set up GUI
public MessServer()
{
   super( "MessServer" );

   enterField = new JTextField(); // create enterField
   enterField.setEditable( false );
   enterField.addActionListener(
      new ActionListener() 
      {
         // send message to client
         public void actionPerformed( ActionEvent event )
         {
            sendData( event.getActionCommand() );
            enterField.setText( "" );
         } // end method actionPerformed
      } // end anonymous inner class
   ); // end call to addActionListener

   add( enterField, BorderLayout.NORTH );

   displayArea = new JTextArea(); // create displayArea
   add( new JScrollPane( displayArea ), BorderLayout.CENTER );

   setSize( 300, 150 ); // set size of window
   setVisible( true ); // show window
} // end Server constructor

// set up and run server 
public void runServer()
{
   try // set up server to receive connections; process connections
   {
      server = new ServerSocket( 12345, 100 ); // create ServerSocket

      while ( true ) 
      {
         try 
         {
            waitForConnection(); // wait for a connection
            getStreams(); // get input & output streams
            processConnection(); // process connection
         } // end try
         catch ( EOFException eofException ) 
         {
            displayMessage( "\nServer terminated connection" );
         } // end catch
         finally 
         {
            closeConnection(); //  close connection
            counter++;
         } // end finally
      } // end while
   } // end try
   catch ( IOException ioException ) 
   {
      ioException.printStackTrace();
   } // end catch
} // end method runServer

// wait for connection to arrive, then display connection info
private void waitForConnection() throws IOException
{
   displayMessage( "Waiting for connection\n" );
   connection = server.accept(); // allow server to accept connection            
   displayMessage( "Connection " + counter + " received from: " +
      connection.getInetAddress().getHostName() );
} // end method waitForConnection

// get streams to send and receive data
private void getStreams() throws IOException
{
   // set up output stream for objects
   output = new ObjectOutputStream( connection.getOutputStream() );
   output.flush(); // flush output buffer to send header information

   // set up input stream for objects
   input = new ObjectInputStream( connection.getInputStream() );

   displayMessage( "\nGot I/O streams\n" );
} // end method getStreams

// process connection with client
private void processConnection() throws IOException
{
   String message = "Connection successful";
   sendData( message ); // send connection successful message

   // enable enterField so server user can send messages
   setTextFieldEditable( true );

   do // process messages sent from client
   { 
      try // read message and display it
      {
         message = ( String ) input.readObject(); // read new message
         displayMessage( "\n" + message ); // display message
      } // end try
      catch ( ClassNotFoundException classNotFoundException ) 
      {
         displayMessage( "\nUnknown object type received" );
      } // end catch

   } while ( !message.equals( "CLIENT>>> TERMINATE" ) );
} // end method processConnection

// close streams and socket
private void closeConnection() 
{
   displayMessage( "\nTerminating connection\n" );
   setTextFieldEditable( false ); // disable enterField

   try 
   {
      output.close(); // close output stream
      input.close(); // close input stream
      connection.close(); // close socket
   } // end try
   catch ( IOException ioException ) 
   {
      ioException.printStackTrace();
   } // end catch
} // end method closeConnection

// send message to client
private void sendData( String message )
{
   try // send object to client
   {
      output.writeObject( "SERVER>>> " + message );
      output.flush(); // flush output to client
      displayMessage( "\nSERVER>>> " + message );
   } // end try
   catch ( IOException ioException ) 
   {
      displayArea.append( "\nError writing object" );
   } // end catch
} // end method sendData

// manipulates displayArea in the event-dispatch thread
private void displayMessage( final String messageToDisplay )
{
   SwingUtilities.invokeLater(
      new Runnable() 
      {
         public void run() // updates displayArea
         {
            displayArea.append( messageToDisplay ); // append message
         } // end method run
      } // end anonymous inner class
   ); // end call to SwingUtilities.invokeLater
} // end method displayMessage

// manipulates enterField in the event-dispatch thread
private void setTextFieldEditable( final boolean editable )
{
   SwingUtilities.invokeLater(
      new Runnable()
      {
         public void run() // sets enterField's editability
         {
            enterField.setEditable( editable );
         } // end method run
      }  // end inner class
   ); // end call to SwingUtilities.invokeLater
} // end method setTextFieldEditable
} // end class MessServer

